Conventionally, there is widely used a disk cartridge having rotatably encased therein a disk used as an information recording medium, such as an optical disk or the like, and that can be loaded into a disk recording and/or playback apparatus while having the disk kept encased therein. Since the disk cartridge has the disk encased in the body thereof, it can protect the disk and easily be loaded into, or unloaded from, the disk recording and/or playback apparatus.
Since the disk cartridge of this type can be loaded into a disk recording and/or playback apparatus while having the disk encased in the body thereof, the cartridge body has formed therein a driving opening through which a disk rotation driving mechanism to rotate the disk is exposed to outside and a write and/or read opening through which a part of the signal recording area of the disk, ranging from the inner to outer radius, is exposed to outside.
Also, the disk cartridge having the disk encased therein has provided therein a shutter member that covers and uncovers at least the write and/or read opening in order to prevent dust or the like from coming into the cartridge body and contaminating the disk.
Further, to prevent the write and/or read opening from being inadvertently uncovered while the disk cartridge is being stored being not loaded in any disk recording and/or playback apparatus and any foreign matter such as the finger or the like from coming into the cartridge body through the write and/or read opening and damaging the disk in the cartridge body, it is proposed to always force the shutter member with a forcing member such as a spring in a direction of covering the write and/or read opening.
Also, for easier installation of the spring member that forces the shutter member, it has been proposed in the Japanese Patent Application Laid Open No. 212872 of 1991 (will be referred to as “Patent Document 1” hereunder) and Japanese Utility Model Application Laid Open No. 83274 of 1987 (will be referred to as “Patent Document 2” hereunder) to provide a spring member integrally on the shutter member in such a manner that the spring member will be secured to the cartridge body when the shutter member is installed to the cartridge body.
In the disk cartridge disclosed in the Patent Document 1, the shutter member is only forced in a direction of covering the write and/or read opening. So, when the shutter member is pushed against the force of the spring member while being held by the hand and fingers, for example, the shutter member will easily be moved in a direction of uncovering the write and/or read opening.
In the disk cartridge disclosed in the Patent Document 2, there is provided a shutter movement limiting member that locks, in the covering position, the shutter member having been moved to a position to cover the write and/or read opening. In this disk cartridge, the write and/or read opening can positively be covered with the shutter member locked in place by the shutter movement limiting member. Since the shutter movement limiting member is provided independently of the shutter member on the cartridge body, however, it adds to the number of parts of the disk cartridge and also leads to a more difficult assembling of the disk cartridge. Also, the cartridge body should have provided therein a space where the shutter movement limiting member is to be installed, that will make it difficult to design a smaller disk cartridge.